Civil liberties and tech advocacy groups have opposed a move by the Department of Homeland Security to collect social media information from certain categories of visitors to the U.S.

“This program would invade individual privacy and imperil freedom of expression while being ineffective and prohibitively expensive to implement and maintain,” wrote organizations like the American Civil Liberties Union, Center for Democracy & Technology and Electronic Frontier Foundation in comments to the Department of Homeland Security on Monday.

The provision allows for collection of information on their online presence from certain categories of visitors in their visa-waiver arrival/departure records (Form I-94W) and their online application for an Electronic System for Travel Authorization (ESTA).

The visa-waiver program enables most citizens or nationals of participating countries to travel to the U.S. for tourism or business for stays of 90 days or less without first obtaining a visa, if they meet certain conditions.

DHS has asked for written comments on its proposal that would add to the ESTA and to Form I-94W the following entry: “Please enter information associated with your online presence—Provider/Platform—Social media identifier,” which visitors can fill optionally. The notice is not clear about the precise information that will be sought, but the groups said the proposal would “appear to solicit applicants’ account names on certain popular social media platforms, and to volunteer any additional account names and platforms they may use.”

Although it is described by DHS as voluntary, the absence of information in the data field could also be possibly interpreted as something worth scrutiny by the authorities, according to analysts.

“Collecting social media data will enhance the existing investigative process and provide DHS greater clarity and visibility to possible nefarious activity and connections by providing an additional tool set which analysts and investigators may use to better analyze and investigate the case,” DHS said in June.

But the groups disagree that the collection will be effective in helping track down potential terrorists from the social media accounts of the visa-waiver applicants. “Individuals who pose a threat to the United States are highly unlikely to volunteer online identifiers tied to information that would raise questions about their admissibility to the United States,” the groups wrote.

In contrast, the program would significantly impinge on the privacy of visitors and lead to an expansion of surveillance activities, according to the groups. The provision also raises the risk of discrimination based on analysis of social media content and connections, which will likely affect people of Arab and Muslim communities, whose usernames, posts, contacts, and social networks will be exposed to close scrutiny.